The Study Of Removal Of Refractory Organic Wastewater By Micro-aeration SBR Cometabolism Method

The composition of refractory organic wastewater are complex, toxicity and their chemical oxygen consumption are very high. The general microbialal most no degradation effect on this kind of wastewater, if these substances without governance discharge to the environment, it will seriously pollutes the environment and threaten human health. With the rapid development of industry and agriculture, increasing amounts of organic matter have been synthesized, there fractory organic matter accounted for a large proportion, is a important question of research on the prevention and control of water pollution. Pentachlorophenol (PCP) wastewater is one kind of representative high toxicity, stable structure, and refractory organic industrial wastewater. Despite the current domestic and international research on the methods of treatment of wastewater containing PCP has made some progress, most of these methods have high energy consumption, it is difficult to control and easily loading to secondary pollution problems. The aim of this study is to propose SBR(Sequencing Batch Reactor) overcome the current method’s drawback, which is preferably suitable for processing of refractory organic wastewater with low energy consumption, low operation cost, low sludge yield biological co-metabolism technology, micro aeration SBR cometabolism. Through the experiment, the factors which influence micro aeration SBR process co-metabolism process PCP treatment efficiency and sludge activity were studied; the optimum operating conditions for stable operation was optimized; the acclimation of micro aerobic granular sludge metagenome library was constructed; micro aeration SBR cometabolism of PCP wastewater treatment, the acclimation in microbial population abundance, diversity, community distribution and phylogeny were studied. With the help of simulation test results and the system dynamic model, the amplification was successfully applied in practical engineering. This study would provide theoretical basis and technical reserves for biodegradation of PCP and other toxic and refractory organics, and provide technical support for the practical engineering design.The asynchronous inoculation method was employed to culture and domesticate granular sludge in the micro aeration SBR cometabolism system. Having been cultured for30d, floc sludge from city sewage treatment secondary sediment tank with synthetic wastewater can reach the full particles, the formation of which has obvious structural characters. With cometabolism substrate, the influent PCP concentration was1mg/L acclimation, not adding cosubstrate carbon source reactor bacteria dissolve dead; reactor adding trehalose, glucose, acetate and yeast extract in the micro aerobic granular sludge has a certain tolerance. The concentration of PCP was gradually increased during acclimatization, the effluent effect from good to poor were trehalose, glucose, yeast extract, acetic acid, when acclimation was completed by the influent PCP concentration of50mg/L in80d. Trehalose as cometabolism substrate, which can obtain higher biomass activity, can produce the dechlorination rate higher stimulation dechlorination reaction resulting in the system. In each PCP acclimation concentration, trehalose could be acclimated degradation time which shortens nearly half time, and the removal rates of PCP, CODCr removal rate and AOX removal rate can reach98%or more.Micro aeration SBR co-metabolism system in long-term operation results showed that restrictive ecological factors, environmental factors and operation parameters would influence the removal rate of PCP. When the concentration of DO in0.3mg/L, ORP maintained at-100mV, adjusting the pH value within the range of6.7-7.5, PCP load is20×10-3kg/(M3·d), trehalose dosage is10mg/L, temperature is30℃, NaHCO3dosage is800mg/L, reaction time is6h, the removal effect of PCP and other pollutants reach the best state. Especially, the DO concentration must be controlled strictly, since the high concentration of DO can cause the micro aerobic granular sludge disintegration. It suggests that the DO is a key factor for operation and control of aerobic granular sludge system.Through the measuring of metagenomem in high-throughput sequencing technology on domestication and micro aerobic granular sludge before and after the acclimation, the PCP micro aeration bacteria in SBR system16S rDNA clone library was consructed. The results showed that bacterial library capacity after acclimation reactor can meet the requirements of prediction. The OTU clustering analysis indicated that microbial community structure, the domestication of reactor advantages of OTU mainly belong to Proteobacteria beta Proteobacteria dechlorinating bacteria (Dechloromonas), microbial species represented by OTU has many advantages in quantity, which belongs to PCP degradation dominant bacteria, and the sequence and PCP degrading bacteria Phanerochate Chrysosporium and Desulfitobaterium dehalogenus bacteria has the highest homology, may be the main role in the process of biodegradation of PCP. Compared to the domestication of reactor, microbial diversity and colony abundance decreased PCP acclimated micro aerobic granular sludge may be related with the changes and PCP toxicity effects of substrate.Based on the Monod equation, a dynamic model of the SBR micro aeration cometabolic degradation of PCP and micro good general dynamic model of aerobic granular sludge were built. The simulation and application of the models in two micro aeration SBR micro was good at the oxygen evolution reaction, the theoretical simulation results and the experimental results are in good agreement, which is above97%; the model of aerobic granular sludge degrading PCP micro aeration SBR system to predict that the increase of particle size is conducive to the improvement of the anaerobic zone and the aerobic zone volume ratio, contributes to PCP degradation and intermediate degradation products; the increase of the concentration of DO is not conducive to the degradation of PCP, TeCP, TCP hig-hchlorophenol, conducive to low-chlorophenol DCP mineralization; active position in excess of trehalose and chlorophenols competition key enzyme, will inhibit the degradation of PCP and its intermediate product; PCP load on key enzymes of co-metabolism and inhibited is more obvious, which will lead to the degradation of PCP incompletely, to accumulate a large number of intermediate products, wastewater and toxic effect degradation incompletely.